One such prior art scanner is described in U.S. Pat. No. 3,970,979, issued Jul. 20, 1976. Other related patents include U.S. Pat. Nos. 3,959,673 issued May 25, 1976; 4,076,998 issued Feb. 28, 1978; 4,990,808 issued Feb. 5, 1991; and 5,048,904 issued Sep. 17, 1991.
The prior art scanner described in U.S. Pat. No. 3,976,979 includes a capacitive drive circuit having an output conductor, a summing junction having an input connected to the drive output conductor, a drive rotor having an elongate axis, a drive stator having a drive coil connected to an input of the summing junction, a sensor rotor having a sensor coil connected to a second input of the summing junction whereby a capacitive feedback loop is provided for modifying a drive signal from the summing junction output.
One problem with the prior art nodding scanners is that their performance data is not always suitable for current sensitive applications.